/***
* Turn a multibase decoded string of bytes into a Cid struct
* @param incoming the multibase decoded array
* @param incoming_size the size of the array
* @param cid the Cid structure to fill
*/
int ipfs_cid_cast(const unsigned char* incoming, size_t incoming_size, struct Cid* cid) {
if (incoming_size == 34 && incoming[0] == 18 && incoming[1] == 32) {
// this is a multihash
cid->hash_length = mh_multihash_length(incoming, incoming_size);
cid->codec = CID_PROTOBUF;
cid->version = 0;
mh_multihash_digest(incoming, incoming_size, &cid->hash, &cid->hash_length);
return 1;
}
// This is not a multihash. Perhaps it is using varints. Try to peel the information out of the bytes.
// first the version
int pos = 0;
size_t num_bytes = 0;
cid->version = varint_decode(&incoming[pos], incoming_size - pos, &num_bytes);
if (num_bytes == 0 || cid->version > 1 || cid->version < 0)
return 0;
pos = num_bytes;
// now the codec
uint32_t codec = 0;
codec = varint_decode(&incoming[pos], incoming_size - pos, &num_bytes);
if (num_bytes == 0)
return 0;
cid->codec = codec;
pos += num_bytes;
// now what is left
cid->hash_length = incoming_size - pos;
cid->hash = (unsigned char*)(&incoming[pos]);
return 1;
}
/**
* gives access to raw digest inside multihash buffer
* @param multihash the multihash
* @param len the length
* @param digest the results
* @returns error if less than zero, otherwise 0
*/
int mh_multihash_digest(const unsigned char *multihash, size_t len, unsigned char **digest,
size_t *digest_len) {
int err = check_multihash(multihash, len);
if (err)
return err;
(*digest_len) = (size_t) mh_multihash_length(multihash, len);
(*digest) = (unsigned char*)multihash + 2; // Always true without varint
return 0;
}
static char *test_multihash_new_is_reversible(void) {
int error = MH_E_NO_ERROR;
int code = MH_H_SHA3_512;
const unsigned char *digest = random_512;
const size_t digest_len = 512 / 8;
unsigned char mh[256];
const size_t mh_len = mh_new_length(code, digest_len);
error = mh_new(mh, MH_H_SHA3_512, digest, digest_len);
mu_assert("creating multihash", error == MH_E_NO_ERROR);
mu_assert("reading code", mh_multihash_hash(mh, mh_len) == MH_H_SHA3_512);
mu_assert("reading length", mh_multihash_length(mh, mh_len) ==
(int) digest_len);
return NULL;
}
